Method of preparing powdered egg albumen



March 19, 1963 D. H. BERGQUIST 3,032,098

METHOD OF PREPARING POWDERED EGG ALBUMEN Filed July 15, 1955 2 Sheets-Sheet 1 INVENTOR I144 12' fle g ymls'f March 19, 1963 .D. H. BERGQUIIS'T 3,082,098

METHOD OF PREPARING POWDERED EGG ALBUMEN Filed July 15, 1955 2 Sheets-Sheet 2 INVENTOR 2s BY Wo RNEY United States Patent r 3,082,098 p METHOD OF PREPARING POWDERED EGG ALBUMEN Dwight H. Bergquist, Springfield, Mo., assignor to Henningsen, Inc}, New York, N.Y., a corporation of Texas Filed July 15, 1955, Ser. N0. 522,336 Claims. (Cl. 99-210) The present invention relates to spray drying and more Presently known methods of dehydrating such products utilize atomizing' devices' which spray the fluid-s into a stream of hot gas. The hot gas dehydrates the spray drop-' lets-*and the remaining solids are precipitated as a dry powder.

It has been found that the'known methods of dehydration have in many instances changed the characteristics of 'theproduct's in undesirable ways. -Known types of spray driers use conventional atomizing devices such as high-pressure nozzles and centrifugal atomizers which subject the l-iquidproduct to considerable homogenizing or'shearingaction -as the liquid product passes there-' through. The present invention provides an improved spray drier which reduces the homogenizing or shearing action and produces a dried product which retains the original characteristics of the liquid product.

One example of the change in functional properties of spray dried products occurs in egg white dehydrated by conventional atomizing devices. A serious loss in the beating power of the egg white occurs so that whipping times'in baking with the" egg white are necessarily greatly lengthened and a significant reduction in cake volume occurs in cakes prepared with the egg white. It is believed that this damage to the egg white is caused by the shear stresses in the liquid egg white existing during its spraying by conventional pressure nozzles and centrifugal atomizers.

Accordingly, an object ofthe invention is to provide an improved method for spray drying;

Another object of the present invention is to provide an improved spray-dried product. I

Another object of the present invention is to provide improved spray-dried eggalbumen.

Other and further objects of the invention will be obvious upon-an understandingof the illustrative embodiment-about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur'to one skilled in-the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration anddescription and-is shown in the accompanying drawings, forming -a part of the specificationflvherein:

FIG. 1 is a diagrammatic view of one embodiment of the spray drier of the invention; p

FIG. 2 is a diagrammatic view of another embodiment of the spray drier of the invention;

FIG. 3 is a side elevational view, partially in section, of an' atomizer connection in accordance with the invention;

FIG. 4 is a front elevational view of the atomizer of the invention;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4;'

3,082,098 Patented Mar; 19, 1963 FIG. 6 is a fragmentary, enlarged sectional view of a nozzle of the atomizer of FIG. 4; and

FIG. 7 is a sectional view of another embodiment of the atomizer.

Referring to the drawing and particularly to FIG. 1, a spray drier 1 is shown having afconventionalenclosed drying chamber 2 into which the liquid product is sprayed for drying by the novel atomizer system 4 of this invention; A hot .gas, such as hot air, is forced 'intodrying chamber'2 from a suitable supply conduit 5 through hot gas inlets 6 in the'wall of drying chamber 2 adjacent atomizer system 4. The hot gas dehydrates the spray droplets emerging from atomizer 4 and carries the evaporated portion out of chamber2 through filterbags7 and outlet 8. The solid portions of the droplets fall downwardly as a powder onto the floor 9 of drying chamber 2 for re moval;

In order to heat the spray droplets to a predetermined temperature during theirdehydration, the'h'ot air from conduit 5 is supplied at a 'hig-htemperature to rapidly heat the droplets and to overcome the evaporative cooling effect of the dehydration. Thus, for example, where egg white is being dried, the hotair has a temperature of about 350 degrees F. in order to heat the droplets to a temperature of about degrees F. I

The two fluid atomizer system 4 replaces conventional pressure nozzle and centrifugal atomizer systems and comprises atomizers '10," atomizer connector 13 on which the atomizer 10 is mounted, fluid supply piping which connects the atomizer connector 13 to a sourceof'the liquid product 12 through a pump 14, and gas piping 15 which connects the atomizer connector 13to a 'sou'rce'of gas 16. The source of gas in the embodiment shown'in FIG. 1 comprises a suitable air compressor17 and a storage tank 18 capable of supplying 'air' to the atomizer 10 at a constant and predetermined pressure. Gases other than air may be used when suitable.

The detailsot a preferred fiorm of the atomizer connector .13 are shown in FIG;'3. The atomizer' connector comprises central liquid conduit 24 adapted for threaded connection at one end to atomizer .10 and at its other end performs the dual function of supplying air to atomizer 10 and of shielding the liquid product in centrJaljliquid conduit24 from the warm drying 'air 44 being directed past atomizer 10 frornconduit 5. As'ncted above, the drying air 44 may have a temperature of about 350 de grees to raise the spray droplets to 110 degrees F. The 350 -degree 1F. temperature is harmful to most food productsandthey cannotbe'subjected to it while passing through the central liquid conduit 24. The air or other gas flowing-through air jacket 40 ins1 1late's' the central liquid conduit, keeping it relatively cool to prevent overheating of the liquid product which would dainageit as well ascoagul-atin'ginany food products;

In order to provide for 'a high-capacity spray driei', it is necessary to provide a liquid spray whi'ch' occupies a substantial part of the 'interior of dryingcliamber 2 and which thus resents amariniumn meerof spray drop-lets to the vaporizingactiori'ofthe heatedgais entering drying chamber 2 through'hotfgas' inlets '6. Two types 'of atomizing' devices are presently used'to provide the widely distributed spray! One of these is a pres sure "nozzle and the other'i s a centrifugal atomizer. The pressure nozzles which 'are operated at pressures" of a thousand p.s.i. or'more and thecentrifugalia-tomizers both subject the liquid produ-cfto shear tfo'rces' "great enough in many cases to cause-a denaturation of the liquid product. The two fluid atomizer 10 of the present nvention provides a widely dispersed spray and it operates lt low pressures of considerably less than 100 p.s.i., as

vill be described below, which subject the liquid product negligible shear forces during the atomization.

A preferred form of low-pressure two-fluid atomizer l0 is shown in detail in FIGS. 4 through 6.

Atomizer comprises a hollow, generally conically haped nozzle face plate 28 fastened to a fluid inlet plate 10 by bolts 22. Nozzle face plate 28 is spaced from nlet plate 20 to provide an enclosed fluid distributing :hamber 31 which distributes the atomizing fluid from nlets 34 to the plurality of nozzles 27 located on the z-ides of nozzle face plate 28. The atomizing fluid is iormally a gas and in the usual case may be air. The luid to be atomized is admitted through fluid inlet 24 into I. central conduit 25 in inlet plate '29 and thence to the lozzles 27 through conduits 26 in inlet plate 20 and nip- :les 35 formed on the inner face of inlet plate 20. Noz- :les 27 are spaced around the conical surface of noz- :le face plate 28 so that they spray the atomized fluid n a diverging pattern. By using a plurality of nozzles .7 rather than a single nozzle, the nozzles may be made maller for a given rate of fluid flow, resulting in beter control of the atomized particle size. The smaller iozzles form uniformly sized particles of a predeternined size while large nozzles form particles of varyng sizes. In order to provide uniform spray drying :onditions, the control of the particle size is very imrortant as the temperatures and drying times of the paricles which depend on the particle size are preferably maintained at uniform and predetermined amounts.

The details of the nozzle 27 are shown in FIG. 6. Dust 26 in nipple 35 carries the fluid product to be ttOITllZBd from conduit 25 across the distributing chamer 31 to nozzle 27. An annularly-shaped opening 36 s left between nipple 35 and the nozzle face 28 to pro- 'ide a passage into nozzle 27 for the atomizing fluid from bamber 31. The atomizing fluid and the fluid product ire mixed in mixing chamber 37 to form the spray dropets. Restricted portion 38 directs the spray formed in mixing chamber 37 outwardly into the drying cham- )BI' 2.

The liquid product to be atomized is supplied to atomzer 10 with the minimum pressure which will insure qual distribution of the product to the nozzles. A pres- .ure of as little as six or seven pounds per square inch las been found suitable. The pressure of the atomizing luid, such as air, is kept as low as possible to prevent hear stresses in the formation of the droplets, since he shear forces cause denaturation of the product, as dis- :ussed above. Using a gas such as air, pressures of from to p.s.i. have been found suflicient to form spray lroplets of satisfactory size for spray drying of products uch as egg whites, egg yolks or whole eggs as contrasted vith the conventional pressures of a thousand pounds or nore per square inch. Pressures of the order of 100 )OllIldS per square inch or less will be referred to herein ncluding the claims as relatively low pressures, while hose of a thousand pounds per square inch or more will re referred to as relatively high pressures.

Another embodiment of the two fluid atomizer is shown [1 FIG. 7 which is used for liquid products which have L tendency to cake on portions of the atomizer shielded rom the drying air stream. This atomizer 61 is gen- :rally similar to the atomizer of FIGS. 4 and 5, however t has a streamlined cross section with rounded edges 0 allow a smooth flow of the spray drying gas over it and o eliminate low pressure areas on the atomizer face at vhich the atomized particles tend to adhere and collect. [he atomizer 61 has a face plate 64 attached to an inlet alate 62 by a single centrally located bolt 67. Both face alate 64 and inlet plate 62 have smoothly rounded edges. fluid distributing chamber 71 is formed between face ilate 64 and inlet plate 62 to distribute the atomizing fluid 'rom inlets 66 to nozzles 69. Conduits 70 in nipples 68 conduct the product to be atomized from inlet 65 in inlet plate 62 to nozzles 69.

The two-fluid atomizer is shown in FIG. 2 installed vertically in a conical drier 49. Hot gas enters the conical drying chamber 50 through gas supply pipe 51 at its edge so that the hot gas is given a circular or cyclonic type motion. The atomizer 52 sprays the fluid to be spray dried downwardly into the hot rotating gas in conical drying chamber 50 and the volatile portions of the particles are evaporated and pass outwardly through the gas exhaust outlet 54 at the top of conical drying chamber 50. Atomizer 52 is connected to a source of atomizing fluid such as air compressor 55 by pipe 56 and to a source 59 of the liquid product to be dried by piping 57 through a low pressure fluid pump 58. The unevaporated or solid portion of the product falls to the bottom of conical drying chamber 50, where it is removed through outlet 60.

It will be seen that the present invention provides a new and improved method for the spray drying of liquid products. The method utilizes a relatively low-pressure spraying means which prepares a dried product which retains important properties of the liquid form, such as, for example, the cooking properties. The method is advantageously applied to many liquid products. It has been found particularly beneficial in the preparation of powdered albumen or egg white. Known drying methods for such products produce a powdered albumen which requires six minutes for proper Whipping in the preparation of an angel cake, while the spray drying process of the present invention produces powdered egg albumen which can be whipped to the desired consistency in one-half this time and which also produces a cake of about twenty-five percent greater volume. An improved two-fluid atomizer or nozzle is disclosed which, while operating at a pressure sufficiently low to prevent denaturization, at the same time provides a large volume spray of controlled spray droplet size for quick drying under controlled conditions. Such a spray is one in which the liquid product is atomized into particles of a predetermined srnlall size and in which the spray pattern has a wide distribution. An improved nozzle connection for the two-fluid atomizer is disclosed in which the second or atomizing fluid is used to provide a heat insulator for the liquid product inlet so that heat may be applied at the atomizer without damaging or coagulating the liquid product in the feed pipes or in the atomizer itself.

As various changes may be made without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. A method of preparing a powdered egg albumen from fluid egg albumen while preserving the natural characteristics of the egg albumen which comprises atomizing the fluid egg albumen by mixing an atomizing gas with the fluid albumen and by spraying the mixture under pressure into a hot gaseous medium, and maintaining the pressure of the atomizing gas and the pressure of the fluid egg albumen at less than p.s.i.

2. A method of preparing a powdered egg albumen from fluid egg albumen while preserving the natural characteristics of the egg albumen which comprises atomizing the fluid egg albumen into uniformly sized particles by mixing the fluid egg albumen with an atomizing gas and by spraying the mixture under pressure into a hot gaseous medium, maintaining the pressure of the atomizing gas between seven and fifteen p.s.i., and maintaining the pressure of the fluid egg albumen at about seven p.s.i.

3. A method of preparing a powdered egg albumen from fluid egg albumen while preserving the natural characteristics of the egg albumen which comprises 5 atomizing the fluid egg albumen into uniformly sized particles bymixing an atomizin'g gas with the fluid albumen and by spraying the mixture under pressure into a hot gaseous medium having a temperature of about 350 F., and maintaining the pressure of the fluid egg albumen and the atomizing :gas at less than 1 00 psi.

4. A method of preparing a powdered egg albumen from fluid egg albumen while preserving the natural characteristics of the egg albumen which comprises atomizing the fluid egg albumen into uniformly sized particles by mixing an atomizing gas with the fluid albumen and by spraying the mixture under pressure into a hot gaseous medium having a temperature of about 350 F., maintaining the pressure of the atomizinig gas between seven and fifteen p.s.i,,- and maintaining the pressure of the fluid egg albumen at about seven psi.

5. The method as claimed in claim 4 in which said atomizing gas is directed along a path surrounding the fluid egg albumen whereby the atomizing 'gas insulates the fluid egg albumen prior to its mixture therewith.

References Cited in the file of this patent UNITED STATES PATENTS 860,929 Merrell et a1. July 23, 1907 1,183,098 Merrell May 16, 1916 1,866,769 Harris July 12, 1932 1,952,236 Clawson Mar. 27, "1934 2,035,673 Schultz Mar. 31, 1936 2,166,070 Littlefie'ld July 11, 1939 2,191,257 Littl-efield Feb. 20, 1940 2,413,420 Stephanofi Dec. 31, 1946 2,531,343 Patterson Nov. 21, 1950 2,630,387 Epstein et al. Mar. 3, 1953 2,645,527 Walters July 14, 1953 FOREIGN PATENTS 824,722 France Feb. 15, 1938 

1. A METHOD OF PREPARING A POWDERED EGG ALBUMEN FROM FLUID EGG ALBUMEN WHILE PRESERVING THE NATURAL CHARACTERISTICS OF THE EGG ALBUMEN WHICH COMPRISES ATOMIZING THE FLUID EGG ALBUMEN BY MIXING AN ATOMIZING GAS WITH THE FLUID ALBUMEN AND BY SPRAYING THE MIXTURE UNDER PRRSSURE INTO A HOT GASEOUS MEDIUM, AND MAINTAINING THE PRESSURE OF THE ATOMIZING GAS AND THE PRESSURE OF THE FLUID EGG ALBUMEN AT LESS THAN 100 P. S. I. 